Light-emitting diodes (LEDs) are of the advantages of low power consumption and long lifespan and are thus commonly used in electronic products. With the progress of science and technology, the electronic devices are now in a trend of compactness and lightweight. However, the conventional LEDs, no matter how small the size of a carrier thereof is, are of a bulky size after a light-transmitting layer is wrapped around the constituent components thereof. This is against the current trend.
To comply with the trend of compactness and light weight, surface mount technology (SMT) is now employed to mount a substrate to which a light-emitting chip is bonded to a flexible printed circuit (FPC). This is shown in FIG. 6 of the attached drawings, wherein a flexible printed circuit A is provide with an insulation substrate B thereon. The insulation substrate B can be for example a rigid printed circuit board (PCB). The printed circuit board is provided on a top surface thereof with a conductor pattern C, which forms a bonding zone C1, a positive electrode zone C2, and negative electrode zones C3. The conductive pattern C is coated with isolation resin D except where the bonding zone C1, the positive electrode zone C2, and the negative electrode zones C3 are located. The bonding zone C1 functions to provide a location for flip-chip bonding of a light-emitting chip. To use, the light-emitting chip is bonded to the bonding zone C1 on the top surface of the insulation substrate B and is electrically connected to the conductor pattern C by connection wires. Thereafter, the light-emitting chip is covered with resin E to complete the packaging process. The conventional structure described above requires adoption of surface mount technology, which needs adhesive application and reflow oven processes to carry out soldering for bonding and mounting the insulation substrate B to the flexible printed circuit. This is susceptible to potential risks of failure soldering between the insulation substrate B and the flexible printed circuit A, leading to increased flaw rate of products and also increasing manufacturing costs. When the flexible printed circuit A and the insulation substrate B are fixed together by soldering, the insulation substrate B occupies a substantial amount of the surface area, leading to increase of surface area of a unit volume, and for applications in a bent or flexed condition, the soldered portions between the flexible printed circuit A and the insulation substrate B become weak points in view of structural strength, leading to undesired separation of the flexible printed circuit A from the insulation substrate B and consequently poor electrical engagement therebetween. Further, the conventional structure is commonly used in an application for a light-emitting strip, wherein up-and-down bending, flexing and stretching occur very often, and the soldered structure of the insulation substrate B soldered to the flexible printed circuit is structurally poor in resisting flexing and stretching.
Thus, the present invention is aimed to overcome the drawbacks of the conventional devices discussed above.